CHICAGO (AP) - The NCAA says the safety of its student athletes is among its core principles.

The college sports association responded to a lawsuit that challenges its handling of head injuries. Attorneys asked a federal judge Friday to let them expand the lawsuit nationwide to include thousands of plaintiffs.

NCAA spokeswoman Stacey Osburn says the association "has been at the forefront of safety issues."

She says it has addressed the issue of head injuries through a combination of playing rules, equipment requirements and medical practices.

Osburn said Saturday the NCAA does not believe the legal action is appropriate.

The motion seeking class-action status was filed in U.S. District Court in Chicago, where the original lawsuit was filed in 2011 on behalf of former Eastern Illinois football player Adrian Arrington and several others.